Internally cooled turbine blades may include passages and vanes (air deflectors) within the blade. These hollow blades may be cast. In casting hollow gas turbine engine blades having internal cooling passageways, a fired ceramic core is positioned in a ceramic investment shell mold to form internal cooling passageways in the cast airfoil. The fired ceramic core used in investment casting of hollow airfoils typically has an airfoil-shaped region with a thin cross-section leading edge region and trailing edge region. Between the leading and trailing edge regions, the core may include elongated and other shaped openings so as to form multiple internal walls, pedestals, turbulators, ribs, and similar features separating and/or residing in cooling passageways in the cast airfoil.
U.S. Pat. No. 6,974,308B2 to S. Halfmann et Al. discloses a robust multiple-walled, multi-pass, high cooling effectiveness cooled turbine vane or blade designed for ease of manufacturability, minimizes cooling flows on highly loaded turbine rotors. The vane or blade design allows the turbine inlet temperature to increase over current technology levels while simultaneously reducing turbine cooling to low levels. A multi-wall cooling system is described, which meets the inherent conflict to maximize the flow area of the cooling passages while retaining the required section thickness to meet the structural requirements. Independent cooling circuits for the vane or blade's pressure and suction surfaces allow the cooling of the airfoil surfaces to be tailored to specific heat load distributions (that is, the pressure surface circuit is an independent forward flowing serpentine while the suction surface is an independent rearward flowing serpentine). The cooling air for the independent circuits is supplied through separate passages at the base of the vane or blade. The cooling air follows intricate passages to feed the serpentine thin outer wall passages, which incorporate pin fins, turbulators, etc. These passages, while satisfying the aero/thermal/stress requirements, are of a manufacturing configuration that may be cast with single crystal materials using conventional casting techniques.
The present disclosure is directed toward overcoming one or more of the problems discovered by the inventors.